1. Field of Invention
The present invention relates generally to ramps used to load and unload shipping and storage containers, and in particular to a ramp which may be attached to a container and pivoted into position.
2. Description of Related Art
The movement and storage of goods throughout the world has been standardized with the use of standard intermodal containers, also known as shipping or storage containers. These containers are built to have standard dimensions, such that they can be transported using a variety of modes of transport, including ships, trains and trucks. The dimensions of the containers are specified in the ISO 668 standard, set by the International Organization of Standards. For example, a container may be loaded in a foreign country, transported via truck from the manufacturer to a seaport, loaded onto a ship then transported via ship to another seaport, unloaded from the ship and loaded onto a train, transported via train to a storage facility, then finally transported via truck to its final destination, where the goods are unloaded.
A container may be loaded and unloaded over an extended period of time, depending on the schedule of the shipper or receiver. At times the containers may be located in semi-permanent locations, such as in a storage facility or outside of a home or business during renovations or construction. The container may be used, for example, to store personal belongings, or it may be used to store construction materials, which must be accessed regularly, but securely locked when not in use. When a container is used for a longer period of time, it may be loaded and unloaded several times while remaining in place. Typically, a forklift or hand truck is used to move the contents in and out of the container.
When a container is loaded or unloaded, it is often removed from the transport vehicle and placed on a dock, placement pad or directly onto the ground. The base of the container may be supported by blocks to elevate and level the container. Regardless of whether blocks are used, the inside floor of the container is at a level above that of the surface on which it is placed; typically, the floor is about 5-7 inches higher.
To bridge the height difference, typically a sheet of plywood or a metal plate is used as a ramp between the inside floor of the container and the outside placement surface. This type of ramp can be a safety hazard, as it is not secured to the container and could slip from the edge of the container, possibly causing injury to a user, or causing damage to product being moved over the ramp. For many containers, such ramps will interfere with the proper closing of the door and will therefore need to be removed prior to closing such doors. It will be appreciated that ramps may be heavy and difficult to lift onto or lower from the edge of the container by hand, depending upon the material used.
U.S. Pat. No. 7,310,843 B1 (Mitchell) describes a ramp which may be secured to a standard shipping container, but it is not permanently secured and it does not include a lifting mechanism to raise it into place. Other ramps include lifting mechanisms, but are not designed to be permanently attached to a container. Examples of ramps with lifting mechanisms are U.S. Pat. No. 4,075,729 (Conner) and U.S. Pat. No. 4,209,869 (Trine et al.).